CICS IMS Database Control Guide

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CICS Transaction Server for z/OS

CICS IMS Database Control Guide

Version 2 Release 3

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CICS Transaction Server for z/OS

CICS IMS Database Control Guide

Version 2 Release 3

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Note!

Beforeusingthisinformationandtheproductitsupports,besuretoreadthegeneralinformationunder“Notices”onpage 203.

Thirdedition(December2003)

ThiseditionappliestoVersion 2 Release 3ofCICSTransactionServerforz/OS,programnumber5697-E93,and toallsubsequentversions,releases,andmodificationsuntilotherwiseindicatedinneweditions.Makesureyouare usingthecorrecteditionfortheleveloftheproduct.

OrderpublicationsthroughyourIBMrepresentativeortheIBMbranchofficeservingyourlocality.Publicationsare notstockedattheaddressgivenbelow.

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User Technologies Department Mail Point 095

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WINCHESTER Hampshire SO21 2JN United Kingdom

WhenyousendinformationtoIBM,yougrantIBManonexclusiverighttouseordistributetheinformationinany wayitbelievesappropriatewithoutincurringanyobligationtoyou.

©CopyrightInternationalBusinessMachinesCorporation1989,2003.Allrightsreserved.

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Preface

Who this book is for

This bookisforanyonewho usestheCICS-IMS DatabaseControlinterface, referred toasDBCTLintherestofthis book.

This bookisintendedto helpyouunderstandDBCTL.It containsguidanceon evaluating, installing,andusingDBCTL.Thisbookalso discussesmigrationfrom localDL/I.

For programminginformationonprogramminginterfacesprovidedbyIMS^™,seethe IMSApplication Programming:EXECDLI CommandsmanualandtheIMS

Application Programming:DL/ICallsmanualmanuals.

What this book is about

Theaimof thisbookisto giveintroductoryandguidanceinformationonevaluating, installing, andusingDBCTL.

This bookisintendedto beused inconjunctionwithexistingmanualsintheCICS^® andIMSlibraries,to whichit referswhereappropriate.

What you need to know before reading this book

Beforeyou readthisbook,you needageneralunderstandingofCICSandIMS.

You canfindgeneralintroductoryinformationintheCICSFamily:General InformationandtheGeneralInformationmanualmanual.Youshouldalso have someknowledgeoftheconceptsofdatamanagement anddatabases. For guidanceonthesetopics, seetheIMSDatabaseAdministrationGuideor the IMS/ESAAdministrationGuide:DatabaseManager.

How to use this book

Probably, atfirst,youwillreadthisbook sequentially.Aspectsof DBCTL,from installationthroughperformanceconsiderations,arepresentedintheorderinwhich you arelikelyto needthem. However,newusersofDL/Ishould skipChapter3,

“Migrationconsiderationsfor DBCTL,”onpage15.

Terms used

In general,thisbook referstoCustomerInformationControlSystemandInformation Management Systemas“CICS”and“IMS”,respectively.CICSusedwithout

qualificationnormallyrefersto theCICSelementof CICSTransactionServerfor z/OS^®.However,whenit isnecessary todistinguishbetweenparticularCICSor IMSproducts,therearethefollowingabbreviations,withaversion andrelease numberwhereappropriate:

CICSfor MVS/ESA^™ referstoIBM^®CICSforMultipleVirtualStorage/Enterprise SystemsArchitecture.

CICS/MVS^®refers toIBMCustomerInformationControl System/MultipleVirtual Storage.

CICS/ESA^®refersto IBMCustomerInformationControlSystem/Enterprise SystemsArchitecture.

IMS/VSrefers toIBMInformationManagementSystem/VirtualStorage.

IMS/ESA^® referstoIBMInformationManagementSystem/EnterpriseSystems Architecture.

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IMS/VSDB/DCrefersto IBMInformationManagementSystem/Virtual Storage Database/DataCommunication.

IMS/ESADM/TMreferstoIBMInformationManagementSystem/Enterprise SystemsArchitectureDatabaseManager/TransactionManager.

MVS^™refers totheIBMMVS operatingsystem.

For definitionsof DBCTL-relatedterminologyusedinthisbook,see.

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Summary of changes

Changesfor thiseditionareindicatedbyvertical linestotheleftofthechanges.

Changes forCICSTransactionServerforz/OS,Version2 Release3

No changesfor thisrelease.

Thereisa minorchangeto theCICS-DBCTLstatistics.See“DBCTLstatistics”on page 148.

IMSVersion7.1takesadvantageof theCICSsingleupdatersyncpointoptimization, which allowsCICStouse single-phasecommit insteadoftwo-phasecommitwhere DBCTListheonly recoverableresourceused ina particularLUW.This avoids writing unnecessarylogrecords,decreasestransaction costandimprovesresponse time. Informationonthis hasbeenaddedto“PerformanceparametersinCICS”on page 158,“SummaryofDBCTLabendsandreturncodes”onpage 112and“PAPL requestandreturncodes”onpage145.

Changes forCICSTransactionServerforOS/390^®,Version1Release3

DFHDBFK,theDCBMgroupcommandfile,wasadded.

Changes forCICSTransactionServerforOS/390,Version1Release2

Thenew DBCTLCONsysteminitialization parameterisdescribed,in“DefiningCICS system resourcesfor DBCTL”onpage22.

Changes forCICSTransactionServerforOS/390,Version1Release1

Thefollowingtopicshave beenaddedorchangedsincetheCICS/ESA 4.1edition:

v Withdrawalofsupportfor localDL/I andbatchshareddatabase.

v DBCTLsupportfor IndoubtWait.

v Supportfor theIMSAIBformat hasbeenextended.

v Chapter8of thepreviousedition,about DBCTLinanXRFenvironment,has beendeletedbecausetheXRFfunction hasnotchanged.If yourequirethat chapter,refertotheCICS/ESA 4.1editionof thisbook.

Changes fortheCICS/ESA 4.1edition

Thefollowingtopicshave beenaddedorchangedsincetheCICS/ESA 3.3edition:

v ACICS-suppliedtransaction, CDBM,usedto issueDBCTLoperatorcommands v ACICS-DBCTLinstallationverificationprocedure,DFHIVPDB

v SpecifyingaDBCTLidentifierduringCICSinitializationorviatheCDBC transaction

v ReleaseofDBCTLthreadsatsyncpointinsteadof tasktermination v IMSAIBcallformat

v Withdrawalofsupportfor IMS/VS2.2withlocalDL/I

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v Newsysteminitialization parametersDSALIMandEDSALIM,whichreplace CDSASZE,ECDSASZE,ERDSASZE,EUDSASZE,andUDSASZEparameters v Migrationscenarios

v Exampletraceentries

v Exampleof DFHSTUPoutput.

Changes fortheCICS/ESA 3.3edition

Thebook hasbeenupdatedto reflectthereplacementof thefollowingsystem initialization parameters:

Obsolete

Replacedby DSASZE

CDSASZEandUDSASZE.

EDSASZE

ECDSASZE,ERDSASZE,andEUDSASZE.

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Chapter 1. Overview of Database Control (DBCTL)

This overviewofDBCTLintroducestheconceptsof theCICS-IMSinterfacethat usesDatabaseControl(DBCTL)under theseheadings:

v “Summaryofthebenefits ofDBCTL”

v “Overviewof DL/IrequesthandlinginCICS”onpage2 v “ConnectingtoDBCTL”onpage3

v “CICS-IMSDBCTLenvironment”onpage3 v “Coordinatorcontrolsubsystem(CCTL)”onpage7

v “Resourcesyoucan accessfromaCICSenvironmentthatincludesDBCTL”on page8

Summary of the benefits of DBCTL

DBCTLisanIMSfacilitythatprovidesanIMS/ESADatabase Manager(IMS/ESA DM) subsystemthatcanbeattachedto CICS,butrunsinitsownaddress spaces.

Thebenefits ofDBCTLaresummarized belowandarediscussedinmoredetailin Chapter2,“Benefitsof usingDBCTL,”onpage 9.

v Releaseindependence—youdonotneed toregeneratetheDL/I supportinCICS ifyouchange toanew releaseofCICSorIMS.

v Accessto moreIMSfunctionsfor CICSusers—DBCTLgivesoneormore CICS systemsonlineaccessto dataentrydatabases(DEDBs)aswellasfull function DL/Idatabases.

v Virtualstorageconstraintrelieffor CICSsystemsthatcurrently containDL/I becauseDL/I codeisoutsidetheCICSaddressspace.

v Improvedthroughputonmultiprocessors,becauseDL/Irequests rununder task controlblocks(TCBs) separatefromthoseused byCICSandbecauseCICSand DBCTLresideinseparateaddressspaces.

v Improvedlogging—DBCTLusesaseparatelog(theIMSlog),soDL/I activity doesnotappearontheCICSsystemlog.ThismeansthatallDL/I informationis ona singlelogandcanbeprocessedusingIMSloggingfacilities.IMSlogging facilitiesincludedual loggingandarewellintegratedwithdatabaserecovery control(DBRC).For moreinformation,see“IMSlogging”onpage 33.

v AbilitytouseCICSsupportfortheextendedrecoveryfacility(XRF).Inaddition,if yourCICSsystemisconnectedtoanIMS/ESADatabaseManager/Transaction Manager(IMS/ESADM/TM)systemto obtainDBCTLsupport,youcanuseIMS XRFfacilities.

v ImprovedfailureisolationbetweenCICSandIMS—aDBCTLfailureshouldnot causeyourCICSsystemtofail.

v Batchjobs canberunasbatchmessageprocessingprograms (BMPs),which areapplicationprogramsthatperformbatchtype processingonlineusingthe sameDBCTLasCICSandsharingitsdatabases.You canusuallyrunthesame programasa BMPorasabatchprogram.UsingDBCTLgivesyouconcurrent accessto IMSdatabases fromBMPsandfromCICS.

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Overview of DL/I request handling in CICS

CICScanaccessDL/Idatabasesinthefollowingways:

v UsingDBCTL

ThisiswhenDBCTLsatisfiestheDL/Irequestissued fromtheCICSsystemby meansoftheCICS-DBCTLinterface.

InstallingandusingDBCTLareintroducedinthis manual(butnotethatyouwill alsoneed torefertootherCICSandIMS/ESAmanualsfor furtherinformation).

v UsingremoteDL/I

RemoteDL/I isdonebymeansof CICSfunctionshippingaDL/I requestto anotherCICSsystem,inwhichtheDL/IsupportcanbelocalDL/I (with CICS/ESA4.1orbelow),remoteDL/I,or DBCTL.SeetheCICS

IntercommunicationGuidefor moreinformationonfunctionshipping,andthe CICSTransactionServerforz/OSInstallationGuideforinformationonadding remoteDL/I support.

Notes:

1. Althoughthesemethodsof accessingDL/I databasescancoexist,aprogram specification block(PSB)canonlycontaindatabasesthatarecontrolledbyone of themethods.

2. CICSTransactionServerforOS/390,Version1Release1onwarddoes not supportlocalDL/I.

CICScanalso accessDL/I databasesinanIMS/ESADatabase

Manager/TransactionManager(IMS/ESADM/TM)system usingtheCICS-DBCTL interface.Thismeansthatyoucanhaveaccessto DL/Idatabasescontrolledby IMS/ESADM/TMwithout needingtouse IMSdatasharing,provided thatCICSand IMS/ESADM/TMareinthesameMVSimage.BoththeIMS/ESADM/TMsystem andtheCICSsystemcaninclude theextendedrecovery facility(XRF).

Figure1illustrates thethreekindsof DL/Irequest.

DBCTLA database DBCTLA

CICSA

CICSB DBCTLB DBCTLB

database CICSB

database

Request #1

Request #2b Request #2a

Request #2a Request #2b

Figure1.DL/IrequesthandlingwithinCICS

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Notes:

1. Request#1isaDBCTLrequestfromCICSAto DBCTLAfor adatabase controlledbyDBCTLA.See“CICS-DL/I router(DFHDLI)”onpage 4fora description ofrequestprocessing.

2. Requests #2aand#2baretwoseparate remote(functionshipped) DL/I requests todatabasescontrolledby,orconnectedto,otherCICSsystems (which maybeinthesameMVS imageoradifferentone).Therearetwoways of issuingsuchrequests:

v Request#2afromCICSAto CICSBforadatabasecontrolledbyCICSB, whereCICSBisCICS/ESA4.1orbelow

v Request#2bfromCICSAto CICSBforadatabasecontrolledbyDBCTLB.

Themostlikelyreasonforusingrequest#2bisifCICSAandCICSBarein differentMVSimages.

Connecting to DBCTL

You canconnectto,anddisconnectfrom,DBCTLusingtheCICS-supplied transaction CDBC.Whenyouhave connectedtoDBCTLbymeansof CDBC,you can issueDL/I requestsfromyourapplicationprograms.Thereisanother

CICS-supplied transaction,CDBI,whichyoucan usetoinquireonthestatusof the connection toDBCTLfromCICS.See“Connection,disconnection,andinquiry transactionsfor theCICSDBCTLinterface”onpage47for informationonusing CDBC andCDBI.

CICS-IMS DBCTL environment

Figure2onpage4givesanoverviewof aCICS-DBCTLinterface.Eachbox

representsanaddressspacerunningwithinasingleMVS system.Themarkedarea betweenthesecondCICSandthefirst BMPisthepoint atwhichCICScomponents endandIMScomponentsbegin.

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CICS-IMS DBCTL environment—description of components

Thefollowingsectionsgive detailedinformationabout eachofthemajor componentsoftheCICS-IMS DBCTLinterface.SeeFigure3onpage7for an illustration ofthesecomponents.Atthispoint,youmaypreferto godirectly to Chapter2,“Benefitsof usingDBCTL,”onpage 9andusethefollowinginformation for referencelater.

CICS-DBCTL interface control components in CICS address space

ThecomponentsoftheCICS-DBCTLinterface intheCICSaddressspaceare:

v TheCICS-DL/Irouter(DFHDLI)

v TheCICSdatabaseadaptertransformer(DFHDBAT) v Thedatabaseresourceadapter(DRA)

CICS-DL/I router (DFHDLI)

TheCICS-DL/Irouter, DFHDLI,formstheinterface betweenyourapplication programs andtheDL/I callprocessor.It acceptsrequests forremote,local,or

DL/I full function databases DEDB

databases

Log RECON

BMP BMP IMS (DBCTL) control region

DLISAS DBRC IRLM MVS/ESA

CICS

Figure2.CICS-DBCTLinterface

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DBCTLdatabaseprocessing.IfDFHDLIdecidesthattherequestisfor DBCTL,it passes therequesttotheCICS-DL/IDBCTLprocessor,DFHDLIDP.Therequest then goestothetask-relateduserexit interfaceandthento theCICSdatabase adaptertransformer,DFHDBAT.(Thetask-relateduserexitinterface isalso referred to astheresource managerinterface(RMI).Thesetermsaredefinedand

comparedinthe, andyou canfindprogramminginformationaboutthetask-related user exitinterfaceintheCICSCustomizationGuide.)

CICS database adapter transformer (DFHDBAT)

Themain responsibilityof theCICSdatabaseadaptertransformer,DFHDBAT(also referred toinIMSpublicationsastheadapter,oradapter/transformer) isto

communicatewiththedatabaseresource adapter(DRA),whichisdescribedbelow.

DFHDBATconstructsparameterlistsfortheDRA.Theseparameterlistsenable CICSto connecttoanddisconnectfromDBCTL,andenableDL/Irequests tobe processed.Tosummarize,DFHDBAT:

v TellstheDRAthatit mustinitializetheinterface toDBCTLinresponsetoa requestfromtheconnection program(DFHDBCON).

v TellstheDRAwhenit mustissuePSBschedulerequests,DL/I requests,and syncpointrequestsinresponsetoarequestfromtheCICS-DBCTLprocessor (DFHDLIDP).

v TellstheDRAthatit mustterminate theinterface toDBCTLinresponsetoa requestfromthedisconnectionprogram(DFHDBDSC).Ifanorderly

disconnectionhasbeen requested,DFHDBATensuresthatallcurrentCICS tasksusingDBCTLcompletebeforetelling theDRAto terminatetheinterface.If animmediatedisconnectionhasbeenrequested,DFHDBATensures thatonly thecurrentCICS-DL/Irequest(s) usingDBCTLcancompletebeforetellingthe DRAtoterminatetheinterface.

CICSmasterterminaloperatorscanuse theCICS-supplied transactionCDBCto connect toanddisconnectfromDBCTL.Theycanalsoautomate connectionto DBCTL, asdescribedin“ConnectingtoDBCTL:overview”onpage45.

Database resource adapter (DRA)

Thefunctionsof thedatabaseresourceadapter(DRA)areto:

v Requestconnectionto,anddisconnectionfrom,DBCTL.

v TellCICSwhenashutdownof DBCTLhasbeenrequested,orif DBCTLhas failed.

v Managethreads.ACICSapplicationthreadprovidesatwo-waylinkbetweenan applicationandDBCTL. WhenaCICStransactionissuesa DL/Irequestto DBCTL,thethreadrepresentsthatCICStransactioninDBCTL. Itidentifiesthe transaction’sexistence,tracesitsprogress,setsasidetheresourcesitneedsto beprocessed, anddelimitsitsaccessibilityto otherresources.

v EstablishcontactwiththeDBCTLaddressspaceandloadtheDRAstartup parametertable.TheDRAstartupparametertableprovidestheparameters neededtodefinetheinterfaceto aDBCTLsubsystem.(See“DefiningtheIMS DRAstartupparameter table”onpage38,foralist ofDRAstartuptable parameters.)

Components of DBCTL in IMS address spaces

ThecomponentsofDBCTLthatresideinIMSaddressspacesare:

v DBCTL

v DL/Iseparate addressspace(DLISAS) v DatabaseRecoveryControl(DBRC) v Internalresourcelockmanager(IRLM).

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DBCTL

TheDBCTLsubsystemcontainssupportandfeaturesrequiredtoprocess full function DL/IdatabasesandDEDBs.Full functionsupportsHSAM, SHSAM, HISAM,SHISAM,HDAM,andHIDAMdatabases.EachDBCTLsubsystemismade upof threeaddressspaces:DBCTL, DLISAS,andDBRC.AsingleDBCTLcan service multipleCICSsystems,butaCICSsystemcanconnect toonly oneDBCTL at atime.ACICSsystemcanconnect tooneDBCTL,disconnectfromit,andthen connect toa differentDBCTL.

DL/I separate address space (DLISAS)

DL/I separateaddressspace(DLISAS), whichisrequiredwithDBCTL,isa separate addressspacethatcontainsDL/I code,controlblocks,buffersfor DL/I databases andprogramisolation(PI),which isDL/I’slockmanager.(Lock

management istheprocess ofcontrollingconcurrentrequests.)You usePIforlock management unlessyouneedtheextrafacilities providedbytheIRLM,which is describedbelow. Forexample,youneedtheIRLMifyouaredatasharingwith anotherDBCTLsubsystem,withlocalDL/I,or withanIMS/VSDB/DCorIMS/ESA DM/TMsystem.SeetheIMSSystemAdministrationGuideortheIMS/ESA AdministrationGuide:Systemfor guidanceinformationonPI.

Database Recovery Control (DBRC)

Database RecoveryControl(DBRC)isanIMSfacilitythatsupportslog

management,recoverycontrol,anddatabasesharingbyprovidingthenecessary informationto subsystems,batchprograms,andutilities.DBRCisrequiredwith DBCTLforlogcontrolandcanoptionally beused fordatabaserecoverycontroland data sharing.See“Databaserecovery control(DBRC)”onpage78forinformation onDBRCandlogging, andtheIMSOperationsGuidefor moregeneralinformation onusingDBRC.

Internal resource lock manager (IRLM)

Theinternalresourcelockmanager(IRLM)isagloballockmanagerthatisa featureof IMSandresidesinitsownaddressspace. Insimpleconfigurations, you donotneedto usetheIRLM;programisolation(PI)lockingissufficient.However, you mustusetheIRLMtomaintaindataintegrityif youaresharingdatabasesat blocklevel.(For VSAMdatabases,a blockisa controlinterval(CI);foranyother kind ofdatabase,it isa physicalblock.)You alsoneedtheIRLMifyouneed to process asetof commondatabasesfrommultipleIMS/ESA(or CICSTransaction Server forz/OS)subsystems.TheIRLMisalso thelockmanagerused by DATABASE2(DB2^®),andsoyoumaypreferto useitwithDBCTLif youalready use, orintendtouse, DB2.SeetheIMSSystemAdministrationGuideorthe IMS/ESAAdministrationGuide:SystemandtheIMSOperationsGuidefor more informationontheIRLM.

Summary of DBCTL components in CICS and IMS

Figure3onpage7 summarizesthemajorcomponentsina simpleCICS-IMS DBCTLenvironment.Each separateboxrepresentsanaddressspace.Allthe componentsshowninFigure3 onpage 7excepttheIRLMaremandatory.

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Coordinator control subsystem (CCTL)

Thecoordinatorcontrolsubsystem(CCTL)isthetransactionmanagement subsystemthatcommunicateswiththeDRA,which inturncommunicates with DBCTL. InaCICS-DBCTLenvironment,theCCTLisCICS.ThetermCCTLisused inanumberof DBCTLoperatorcommandsandintheIMSmanuals.CICSusersof DBCTLshouldtakethetermCCTLto meana CICSsystem thatisattachedtoIMS bymeansof DBCTL.

Shipped with CICS Shipped with IMS CICS address space IMS address spaces

D D R D D D D D I

F F M F R B L B R

H H I H A C I R L

D D D T S C M

CICS L L B L A

I I A S

D T

P

P I

CICS IMS

LOG LOG

Figure3.MajorcomponentsofasimpleCICS-IMSDBCTLenvironment

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Resources you can access from a CICS environment that includes DBCTL

Figure4summarizestheresourcesyou canaccessfromaCICSenvironment that includesDBCTL.

AsingleCICStask canuseDB2tables,IMSdatabases(usingDBCTLorremote DL/I),andCICS-managedlocalorremoteresources(for example,VSAMfiles).

TheCICS-DB2andtheCICS-DBCTLinterfacesaresimilar inthatthey bothusethe task-related userexitinterface,andhave atwo-phasecommitprocess.However, they differina numberof respects.Forexample,CICSsupports DBCTLand remoteDL/I,andhastodetermineatPSBscheduletimewhichof themisbeing used.Formore information,see“Othermethods foraccessingDL/I”onpage15.

DEDB DL/I full

function database

DBCTL

DB2 VSAM

files

GSAM files

CICSA CICSB CICSC BMPX BMPY

DB2 database

Figure4.ResourcesyoucanaccessfromaCICSenvironmentthatincludesDBCTL

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Chapter 2. Benefits of using DBCTL

Support forlocalDL/IandbatchshareddatabaseiswithdrawninCICSTransaction Server. Thebenefits ofDBCTLoverlocalDL/Ifallintothefollowingmain

categories:

v “Functionalbenefitsof DBCTL”

v “Systemavailabilitybenefitsof DBCTL”onpage 13 v “PerformancebenefitsofDBCTL”onpage14

DBCTLprovidesCICSuserswithadditionalfunction,arelease-independent interface,noDL/IcodeintheCICSaddressspace,improvedthroughputon multiprocessors,andmoreflexibleoperations.

Functional benefits of DBCTL

Thefunctionalbenefits thatDBCTLoffersareintheareas of:

v “Dataavailability”

v “Batchmessageprocessingprograms(BMPs)”

v “Systemservicerequests”

v “Accessto dataentrydatabases(DEDBs)”onpage10

Data availability

Previously,if youdidnotuseDBCTL,andadatabasewasunavailablewhenCICS tried toscheduleaprogramspecificationblock(PSB),thetransactionreceiveda returncode tosay thattheschedulehasfailed.DBCTLenablesCICStotake advantageof thedataavailabilitythatIMSprovides;youcansuccessfullyschedule a PSB,eventhoughsomeofthedatabasesusedinthatPSBareunavailable.

Schedulingfor databaserecovery ismoreflexiblebecausedatabaseblocks (orCIs) thathave hadreadorwriteerrorsarestillavailableafteraDBCTLrestart.

See“Enhancedscheduling”onpage99for moreinformationondataavailability andthesystem servicerequestsyoucan useinconnection withit.

Batch message processing programs (BMPs)

Runningbatchjobs(bothCICSshareddatabaseand“native”IMSbatchjobs) as BMPsenables youtousesystem servicerequests,suchassymboliccheckpoint (CHKP)andextendedrestart (XRST),andtoaccessGSAMdatabases,whichyou couldnotdowithCICSshareddatabase.WithBMPs,alllogging goestoa single log(theIMSlog),whicheliminatestheneedfor separatebatchlogs.BMPsalso supportautomaticbackout,andautomaticrestartfromthelastcheckpoint(without requiring JCLchanges).BMPscommunicatedirectly withtheDBCTLaddress space instead ofaccessingdatabasesthroughCICS,andenableconcurrentaccessto databaseswithout theneedtouseIMSdatasharing.Using BMPsgivesa performanceadvantagecomparedwiththesameprogramsthatranasCICS shareddatabasejobs,bothintermsof theelapsedtimeof thebatchjobs

themselves,andintermsof transactionresponseandthroughput,becausetheydo notdelaytheCICSonlineworkloadasmuch.See“Batch messageprocessing programs (BMPs)”onpage102for moreinformation.

System service requests

Your CICSapplicationprogramscanusethefollowingIMSsystemservice requests inadditionto thoserelatedto dataavailability:

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v DEQ(initscommandorcallformat) releasessegmentsthatwereretrieved using theLOCKCLASSkeywordortheQcommandcode.LOCKCLASSandQenable anapplicationprogramtoreservesegmentsforitsuse.

v LOG(initscommandorcallformat) canbeusedtowritearecord froman applicationprogramto theIMSlog.Youmaypreferto usethisinsteadof EXEC CICSjournalcommandssothatallyourDBCTLinformationisontheIMSlog insteadof theCICSlog.

SeeChapter7, “Applicationprogrammingfor DBCTL,”onpage 93for more informationonusingtheserequests.

Access to data entry databases (DEDBs)

Dataentrydatabases(DEDBs)providethesamefeaturesasHDAMdatabases (withtheexceptionsof secondaryindexingandlogical relationships).Theyalso have anumberofadvantages.UsingDEDBsenables youtohave verylarge databases withhighavailability.DEDBsaredesignedtoprovideefficient storage andfast onlinegathering,retrieval,andupdateofdata, usingVSAMentry sequenced datasets(ESDSs).

DEDBs arehierarchicdatabasesthatcancontainupto127segment types.Oneof thesesegmentsisalwaysa rootsegment.Theremaining126segmentscaneither bedirectdependent(DDEP)segments,or125DDEPsegmentsandonesequential dependent(SDEP)segment.ADEDBstructure canhaveasmanyas15

hierarchicallevels.

DEDBs aremade upof databaserecordsstoredina setofupto240areas.Each areacontainsarange ofdatabaserecords(whichyoucanspecifyusingtheDEDB randomizingroutine)thatcontaintheentirelogicalstructure forasetof root

segmentsandtheirdependentsegments.Areasareindependentof eachother, are individually recognized,canbeaccessedbymultipleprogramsandDEDButilities, arethebasisforrecovery procedures,andarelargelytransparenttoapplication programs.

DEDBs providethefollowing advantages:

v Largedatabases

– Areascanbeaslarge as4 gigabytes,andbecauseyoucan haveupto240 areasinasingledatabase,youcanuseverylarge databases,whichyou wouldhaveto partitionifyouwere notusingDEDBs.

v Flexibledesign

– Eachareacanbedesignedto meetyourstorage,availability,performance, andapplicationneeds.Areascanbeseparatelyreorganizedandreacquired.

– YouusetheDEDBdirectreorganizationutilitytophysicallyreorganizeDEDBs toreduceESDSfragmentationwithout takingthem offline.

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v Increaseddataavailability

– IfaDEDBareaisnotavailable, aPSBrequiringthatdatabasecan stillbe scheduledprovidedtheareaitrequiresisnottheonethatisunavailableand, ofcourse,thedatabaseitselfisavailable.APSBthatrequires anunavailable areaisstillscheduled,andreceivesastatuscode indicatingthecondition.

Youcanthereforedelayrecoveryuntilit isconvenientto taketheareaoffline.

– Youcanhaveupto sevencopies ofthesamearea.Eachcopyiscalledan areadataset(ADS)andallareautomaticallymaintainedinsynchronization.

Thisiscalledmultipleareadataset(MADS)support. Writeoperationsare donetoeachADS,butreadoperationsaredonefromonly oneADS.With MADS,readandwriteerrors aremuchlesscommon because,if datacannot bereadfrom,or writtento,thefirstcopy,thenextcopywillautomatically be used.Readerrorsaretransparentto applicationprograms (exceptintherare instancewhereareadoperation isunsuccessfulwithallADSs).

– YoucanuseDEDButilities,whicharerunonanareabasisandcanberun onlineconcurrentlywithonlineupdate.Thishelpsto reducethetimefor which areashave tobetakenoffline.Forexample,youcanavoidusingoffline databaserecovery byusingtheDEDBareadatasetcreateutility.Thisonline utilitymakesanew correctedcopyof anareafromexistingcopiesof that area.Itcreatesoneormorecopies frommultipleDEDBADSsduringonline transactionprocessing,enablingapplicationprograms tocontinuewhilethe utilityisrunning.

– YouusetheDEDBinitialization utilitytoinitializeoneor moredatasetsor one ormoreareasof aDEDBoffline.

– YoucanusetheDEDBareadatasetcompare utilityifyoususpectyoumay haveproblemswithcompatibility ofdata.It comparescontrolintervals(CIs)of differentcopies ofanarea,andlistsalltheCIs thatdonothave equal

content.Inthecaseofunequalcomparison,fulldumpsofuptoten unmatchedCIsareprintedoutonthedeviceyouhavespecified.

v Efficientdataretrievalandentry

– DEDBattempts tophysicallywriteDDEPsegmentshierarchicallyinthesame CIastheparent segment,whichcanmakeretrievalfaster.

– TheSDEPsegment(locatedat theendoftheADS)isdesignedespeciallyfor fast,online,massinsertinapplicationssuchasdatacollection,auditing,and journaling.This isbecauseSDEPsegmentsfor anareaarestoredrapidly, regardlessoftherootonwhichthey aredependent.For example,ina bankingapplication,transactiondatacanbecollectedduringthedayand insertedasSDEPsinanaccount database.At theendof theday,these transactionscanbereprocessedbyfirstretrievingthemusingthesequential dependentscanutility.ThisonlineutilityretrievesSDEPsegmentsinmass andcopiesthemto asequentialdataset.Youcanthenprocess thisdataset offlineusingyourown programs;forexample,for astatisticalanalysis.The areainvolvedremains availablewhiletheutilityisrunning.

– YoucandeleteSDEPsusingtheDEDBsequentialdependentdeleteutility, whichdeletesSDEPsegmentswithin aspecifiedlimitofaDEDBarea.

– Theability tousehigh speedsequentialprocessing (HSSP),whichis availablefromIMS/ESAVersion3 onwards.HSSPisusefulwithapplications thatdolargescalesequential updatestoDEDBs.HSSPcanreduceDEDB processingtime,enables animagecopytobetakenduringasequential updatejob, andminimizestheamountoflogdatawrittento theIMSlog.For furtherguidance,see“Highspeedsequential processing(HSSP)”onpage 162.

v Improvedperformance

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– PathlengthisreducedbecauseDEDBsusetheMVSDataFacilityProduct (MVS/DFP^™)MediaManageroffering.

– Youcanimprovespeedofaccess,orconcurrentaccess,toDEDBsbytuning DEDBbufferpool specifications.(See“DEDBperformanceandtuning considerations”onpage161.)

– Loggingoverheadisreducedbecauseonlyafter-imagesareloggedand becauseloggingisdone duringsyncpointprocessing only.

– Theamountof I/Oneededforeach SDEPsegmentinserted canbevery low, becauseSDEPsaregatheredfromvarioustransactions,storedinlast-in first-outorderinonebuffer,andarewrittenoutonlywhenthatbufferisfull.

Thismeansthatmanytransactions“sharethecost” ofSDEPwrites.

– MostDEDBprocessingisdoneinparalleltoallowmultithreading. Writesto thedatabasearedonebyanumberyouspecify(upto255)of parallel processescalledoutputthreads.Furthermore,theDEDBsarenotupdated duringapplicationprogramprocessing,buttheupdatesarekept inbuffers untilasyncpoint occurs.(See“When updatesarewrittento databases”on page79.)This meansthatwaitingapplicationscanbeprocessedsoonerand improvesthroughputonmultiprocessors.

– DEDBshavetheirown resourcemanagerandnormallyneed tointeractvery infrequentlywithprogramisolationor theIRLM(unlessyouareusingblock levelsharing). DEDBsmaintaintheirown bufferpool.

– Youcanusesubsetpointersinyourapplicationprogramstospeedup processing.Amajorprobleminsomeapplicationsistheneedtoprocess long twinchains ofsegments.Occasionallydatabasedesignmust bemodified becausesomedatabaserecordshave excessivelylongtwinchains.Subset pointersgivedirectaccessto subsetsoflongtwinchainsof segments,which canspeedupapplicationprocessingbecausesegmentslocated infrontof the subsetdonothave tobesearched.Eachpointerpointsto thefirstoccurrence ofasubset inarange ofdirectdependentsegments.See“Commandcodes tomanagesubsetpointers inDEDBs”onpage96and“Keywordsand correspondingcommandcodes”onpage98forinformationaboutusing subsetpointersinapplicationprograms.(SeetheIMSDatabase

AdministrationGuideor theIMS/ESAAdministrationGuide:Database Managerforguidanceondatabasestructure.)

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System availability benefits of DBCTL

Thebenefits thatDBCTLoffersintheareaofsystemavailabilityare:

v “Releaseindependentinterface”

v “Improvedsharingof databasesbetweenmultipleCICSsystems”

v “Failureisolation”

v “Operationalflexibility”

v “AbilitytouseXRF”onpage14

Release independent interface

You donotneedto regeneratetheDBCTLinterface everytime youupgradeyour CICSorIMSsystem.

Improved sharing of databases between multiple CICS systems

WithDBCTL, sharingofdatabasesbetweenmultipleCICSsystemsisimproved.

CICSsystemsinthesameMVSimagecanshare databaseswithotherCICS systems,withbatch(asBMPs),andwithIMS/ESATMwithoutthe needforIMS datasharing.PerformancewithDBCTLisbetterthanusingCICSdatabase-owning regions(DORs)withmultiregionoperation.

Failure isolation

Theinterface isdesignedsothatafailureinCICSshouldnotcauseDBCTLto fail, anda failureinDBCTLshouldnotcauseCICSto fail.

Operational flexibility

CICSandDBCTLareindependent ofeachother; thatis,CICScanberunning while DBCTLisnot,andviceversa.ACICStransaction,CDBC,isprovidedfor you to connectto,anddisconnectfrom,DBCTLdynamically.Another CICStransaction, CDBI,enables youtoinquireonthestatusoftheconnection.

DBCTLenablesyouto doanumberofoperationsonline,including:

v Onlineimagecopy v Onlinechange

v OnlinereorganizationforDEDBs.

Theseutilitiesaresummarized below,see“IMSdatabaseutilities”onpage83for more information.

Online image copy utility

Theonlineimagecopyutility isused tocreateanas-iscopyofyourdatabasewhile it isbeingupdated.Thecopycanthenbeused forrecovery purposes.Thisutilityis used forHISAM,HDAM,andHIDAMdatabasesonly.

Online change utility

In manyinstallations, itisimportantfor theonlinesystemtobeisavailabletousers for mostof theday.Theonlinechangeutilityenables youtoupdateACBLIBs,which contain PSBsanddatamanagementblocks (DMBs),andsecurityinformation belongingto fullfunctiondatabases,without bringingdownthesystem.For

guidanceinformationonthisutility,seetheIMSSystemAdministrationGuideorthe IMS/ESAAdministrationGuide:SystemandtheIMSUtilitiesReference:Database manualmanual.

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Online reorganization for DEDBs

As mentionedin“Access todataentrydatabases(DEDBs)”onpage10,theDEDB directreorganizationutilityenablesyouto reorganizeDEDBswithouttakingthem offline.

Ability to use XRF

DBCTLuserscanuseCICSor IMSsupportfor theextendedrecoveryfacility(XRF) ineither ofthefollowingways:

v StandardDBCTL,inwhich theactive isa standardDBCTLsubsystem.The

“alternate”issimplyanotherstandardDBCTLsubsystemthatispreinitializedand waitingfor arestart command.Youuse thismethodwithor withoutfullCICS XRFsupportandyoucanhavemorethanonepreinitialized DBCTLinthesame MVSimage.(Thismethodisforuserswhodonot haveanIMS/ESADM/TM system.)

v IfyourCICSsystemisconnectedto anIMS/ESADM/TMsystem toobtain DBCTLsupport,you canuseIMSXRFfacilities. Inthiscase,youractiveand alternateDBCTLsubsystemsarethestandardIMSactiveandalternate.(This methodisforuserswhoalready haveanIMS/ESADM/TMsystem.)

SeeChapter6, “Recoveryandrestartoperationsfor DBCTL,”onpage73for more information.

Performance benefits of DBCTL

Thebenefits thatDBCTLoffersintheareaofperformanceare:

v “Virtualstorageconstraintrelief”

v “Improvedthroughputonmultiprocessors”

Virtual storage constraint relief

Previously, ifyoudidnotuseDBCTL,DL/I codeanditsassociatedcontrolblocks (includingDBRC) residedintheCICSaddressspace.WithDBCTL,allthis is movedoutof theCICSaddressspaces,freeingvirtualstoragewithin CICSsystems thatpreviously containedlocalDL/I.

Improved throughput on multiprocessors

Because thecomponentsoftheCICS-DBCTLinterface resideinseparateaddress spaces and,becauseDBCTLusesaseparatetask controlblock(TCB)for each applicationthread,throughputonmultiprocessorsisimprovedandtherecanbe more concurrentactivity.See“TuningaCICS-DBCTLsystem” onpage 158for more informationonthread andTCBperformanceconsiderations.

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Chapter 3. Migration considerations for DBCTL

This sectioncoversmigrationfromaCICSsystemwithlocalDL/I,toa CICS TransactionServerfor z/OS,Version2Release3system withDBCTL.

v “Othermethods foraccessingDL/I”

v “CICS-IMSreleasecompatibility”

v “PossiblemigrationpathstoCICSTransactionServerfor z/OS,Version2 Release3withDBCTL”onpage 16

v “Suggestedmigrationprocedureto DBCTL”onpage 17 v “Planningyournew DBCTLsetup”onpage 18

v “SettinguptestandproductionsystemsforCICSDBCTL”onpage19

SeeAppendixA,“Migrationtask summaryfor DBCTL,”onpage165fora checklist of taskstobedoneto migratetoDBCTL,andalist offallbackconsiderations.

SeetheCICSTransactionServerforz/OSMigrationfromCICSTSVersion2.2and theIMSReleasePlanningGuideforinformationonmigratingto CICSTransaction Serverfor z/OS,Version2 Release3 andtoIMS/ESArespectively.

Other methods for accessing DL/I

Remote databasesupportremainsinCICSforfunction-shippedDL/Irequests.Your remotedatabasescanbemanagedeither bylocalDL/I (iftheremoteCICSis CICS/ESA 4.1or below)orbyDBCTL.

Function shippingsupportstheadditionalsystemservicerequests,DEDBrequests, andenhancedscheduling(usuallyknownas“dataavailability”)supportedbya DBCTLenvironment,allof whicharedescribedinChapter7,“Application programming forDBCTL,”onpage93.

Withdrawn support of local DL/I and shared database

CICSTransactionServerdoesnotsupportlocalDL/I orbatchshareddatabase.

Batch jobsthatusetheCICSshareddatabasefacilitycannotaccessdatabases ownedbyDBCTL.If youwantto useCICSshareddatabasejobs withDBCTL,you must migratethemtorunasBMPs,whichcommunicatedirectlywiththeDBCTL address space.

CICS-IMS release compatibility

Thestartingpoint formigrationisa CICSsystem runningwithlocalDL/I.Theaimis to installCICSTransactionServerfor z/OS,Version2Release3 andIMS/ESA Version6 orlater.Table1shows whichCICSandIMSreleasescanbeused together, andwhethertheycanbeusedwithDBCTL,localDL/I,or both.

Table1.CICS-IMSreleasecompatibility

CICS LocalDL/I DBCTL

CICSTransactionServerfor OS/390,Version1Release1

---- IMS/ESA3.1IMS/ESA4.1

IMS/ESA5.1IMS/ESA6.1 IMS/ESA7.1

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Table1.CICS-IMSreleasecompatibility (continued)

CICS LocalDL/I DBCTL

IMS/ESA7.1 CICSTransactionServerfor

z/OSVersion2Release1

IMS/ESA7.1 CICSTransactionServerfor

z/OSVersion2Release2

CICSTransactionServerfor z/OS,Version2Release3

Anyattemptto connectCICS,withstorageprotectionactive,to aDBCTL

subsystemrunningIMS/ESA3.1resultsinCICSterminatingtheconnectionattempt abnormally. MessageDFHDB8118withreturncode4issent totransientdata destination CDBC,indicating thatCICSdetected thatthereleaseof IMS/ESAdoes notsupporttheMVSsubsystemstorage-protectionfacility.CICSonlyallows connection tothis DBCTLsubsystemifstorageprotectionisturned off.

Possible migration paths to CICS Transaction Server for z/OS, Version 2 Release 3 with DBCTL

This sectionoutlinessomepossiblemigrationscenariostoCICSTransactionServer for z/OS,Version2 Release3 withDBCTL, accordingto yourcurrentsetup.

v “CICSwithlocalDL/I”

v “CICSwithlocalDL/Ianddatasharing”

v “CICSwithshareddatabase”

v “CICSwithIMSdatasharingandbatch”onpage17 v “CICSwithfunction shipping”onpage17

v “CICSwithIMS/ESADM/TM”onpage17

CICS with local DL/I

CICSwithlocalDL/I:

1. CICS/ESA 4.1withlocalDL/IwithIMS/ESAVersion4orbelow

2. CICS/ESA 4.1withlocalDL/IwithIMS/ESAVersion3orlaterandDBCTL (optional)

3. CICSTransactionServerforz/OS,Version2 Release3withDBCTL.

CICS with local DL/I and data sharing

1. CICS/ESA 4.1withlocalDL/IwithIMS/ESAVersion4orbelowdatasharingin a single-MVSenvironment

2. CICS/ESA 4.1withlocalDL/IwithIMS/ESAVersion3orlaterandDBCTLwith data sharing(optional)

3. CICSTransactionServerforz/OS,Version2 Release3withDBCTLwithout data sharing.

CICS with shared database

1. CICS/ESA 4.1withlocalDL/IwithIMS/ESAVersion4orbelowCICSshared database

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2. CICSTransactionServer forz/OS,Version2 Release3 withDBCTLand BMPs—CICSshareddatabaseprogramsconvertedto BMPs.

CICS with IMS data sharing and batch

1. CICS/ESA 4.1withlocalDL/IwithIMS/ESAVersion4 orbelowanddata sharingwithbatchina single-MVSenvironment

2. CICSTransactionServer forz/OS,Version2 Release3 withDBCTLandBMPs without datasharing—batchprogramsconvertedto BMPsina single-MVS environment.

CICS with function shipping

1. CICS/ESA 4.1withIMS/ESAVersion4orbelow, localDL/I—multipleMRO regions—TORs,AORs,andDORs

2. MultipleCICSTransactionServerfor z/OS,Version2Release3systemsusing DBCTL—DBCTLreplacesDORs.

CICS with IMS/ESA DM/TM

Scenario 1

1. CICS/ESA 4.1withlocalDL/IandIMS/ESADM/TMversion4 orlaterdata sharing(possiblyinamulti-MVSenvironment)

2. CICSTransactionServer forz/OS,Version2 Release3 withIMS/ESATM Version6 orlaterwithDBCTLinasingle-MVSenvironment.

Scenario 2

1. CICS/ESA 4.1withIMS/ESADM/TMVersion3orlaterwithLU6.1ina single-MVSenvironmentormulti-MVS

2. CICSTransactionServer forz/OS,Version2 Release3 withIMS/ESADM/TM Version6 orlaterwithDBCTL(applicationprogramrewritten) ina single-MVS environment.

Suggested migration procedure to DBCTL

If youalreadyuseCICSwithDL/I,asuggestedmigrationpathisasfollows:

v InstallMVS(without changingyour CICSor IMSsystems).

v InstallIMS/ESAVersion4(Version5does notsupportlocalDL/I).

v InstallCICS/ESA 4.1withIMS/ESAVersion4 runninglocallyandputthese systemsintoproductiontogether.(Atthisstage,therearenogreatchangesin theCICS-DL/Ienvironment.)

v Convertto DBCTL.

v InstallCICSTransactionServerfor z/OS,Version2Release3.

You willprobably wantto migratetoDBCTLinstages, perhapsasfollows:

1. Set upa testsystem.If youalreadyhavea testsystemthatisusedfor testing new applications,considerusingit fortestingmigrationtoDBCTL.

2. If youdonotwanttobeginwitha testsystem,beginbysettingupa trial productionsystem,perhapsoneyoualreadyusefor testingexistingproduction applicationproblems.

3. Set upa productionDBCTL.

You then:

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v GenerateDBCTL,DLISAS, andDBRC.

Youmust useDBRCwithDBCTL.IfyouarenotfamiliarwithusingDBRC,you shoulduseit initiallyjust tocontrollogfacilities.Todothis,specifySHARECTL whenyouinstallDBRC,butdonotregisterdatabases.

v Decidewhich applicationstomigrate.

v Takefullimagecopies ofdatabasesbeforemigratingthemto useDBCTL.Thisis becauseinformationfor CICS-DL/IdatabasesisonboththeCICSandtheIMS logs.TakinganimagecopywillensurethattheRECONisupdated, and informationforthatdatabasewillbefromtheIMSlogonly.SeetheIMS OperationsGuideforinformationontakingimagecopies,andtheIMSUtilities Reference:Databasemanualmanualfor informationontheutilitiesyoucanuse todoso.

v ConvertCICSshareddatabaseprogramsto BMPs.

v Convertanyprograms thatuseDFHFCTYPE=DLImacrosto issueDL/I commandsorcallsinstead.

v ConvertproductionCICSTransactionServerfor z/OS,Version2Release3 systems.

v TuneCICS-DBCTL.

v Convertbatchjobsto BMPs(theymustissuecheckpoints).

v WhenmigratingyourCICSshareddatabaseprogramsor“native”IMSbatch programsto BMPs,definePSBs inDBCTLsecuritygeneration.

Note: If youruntheapplicationwithCICSLocalDL/I(which IMStreats asa batchjob),IMSallowspathinsertswithout thePROCOPT=Pparameter.

IMSissuesstatuscodeAMif aCICSonlineprogramoraCICSshared databaseprogramissuesanISRTcall withtheDcommandcodewhen theprogramdoesnothave thePROCOPT=Pparameterspecifiedinthe DBPCBthatwasreferencedinthecall.IMSbatchprograms, however,do notneed thePROCOPT=PparametertoissueanISRTcall withtheD commandcode unlesstheprogramusesfieldlevelsensitivity.

If youthenconverttoDBCTL, andruntheapplicationinaBMP region (which IMStreats asonlineprocessing ratherthanbatch),youareno longerpermittedto usepathinsertswithout thePROCOPT=Pparameter.

Forinformationondoingthis,seeChapter8, “SecuritycheckingwithDBCTL,”on page115.

v ConsiderDEDBsfornew applications.

Planning your new DBCTL setup

v IfyouarerunningmultipleCICSregions,each withitsown copyof localDL/I, youarerecommendedto migrateallyourlocalDL/I systemstousea single DBCTL.Ifyou arerunningthesameapplicationsthatschedulethesamePSBs oneachofyour CICSsystems,butaccessdifferentinstances ofthesame databases,migratingtoasingleDBCTLmeansthatyouwillneedaseparate DBDandseparate PSBsfor eachinstanceofadatabase.However, your

applicationscouldcontinueto schedulethesamePSBsbecausethereisaCICS globaluserexitavailableto DL/Iuserswhichmayhelpwithmigrationtoasingle DBCTLinthiscase.ItiscalledXDLIPRE,andit enablesyouto changethePSB nameand/or theSYSIDthattheapplicationprogramhasscheduled atexecution time.AppendixE,“Usingglobaluserexit XDLIPREtochangePSBto be

scheduled,”onpage179containsanexampleofXDLIPREthatyou cancopy

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andmodify.Notethatthis exampleisprovidedfor guidanceonly.SeetheCICS CustomizationGuideforprogramminginformationonusingtheseexits.

v Youhave aremoteDL/I environment,inwhichyouarerunningmultipleCICS AORsthatfunctionship DL/Irequeststo aDL/I resourceowningCICSregionin thesameMVSimage.In thiscase,replacetheDL/Iresource-owningregionwith DBCTL.However,if youarefunctionshippingDL/Irequests toaDL/I resource owningCICSregionina differentMVSimageyoucannotreplacetheDL/I resourceowningregionwithaDBCTLsubsystem.ThisisbecauseCICSand DBCTLcanonly communicatewitheach otherwhentheyareinthesameMVS image.However,theDL/Iresource owningCICSregionmust useDBCTLinstead oflocalDL/I,asshown inFigure5.In thiscase,youkeeptheDOR, butit

communicateswithDBCTL;thatis,DBCTLreplaceslocalDL/I,butnottheDOR.

v CICSTransactionServerforz/OS, Version2Release3systemsrunningina separateMVSimagefromDBCTLmustfunctionship theirDL/Irequests toa CICSTransactionServerforz/OS, Version2Release3system locatedinthe sameMVS imageasDBCTL.

v Ifyouwantbatchprograms torunconcurrentlywithCICS,andyoudonot alreadyuseIMSdatasharingorDBRC:

– InstallDBRCintheexistingCICSsystemandbecome familiarwithit before migratingto DBCTL;or

– InstallDBCTLanduseDBRC tocontrollogsonly.Runthebatchprogramsas BMPs.Whenyouarefamiliarwiththis environment,extendyourusageof DBRCto controldatabaseintegrity.

v Youhave anIMSdatasharingenvironment,inwhichyouarerunningmultiple CICSsystemsthataredatasharingwithoneanotherandwithbatch,andallthe datasharingistakingplacewithin asingle-MVSenvironment.Inthis case,you couldconsidermigratingcompletelyto asingleDBCTLwithinanMVS image insteadof usingdatasharing. Ifyoudothis,migratealltheDL/Ibatchjobs involvedtoBMPs,which willsimplifylogmanagement.

YoucanuseIMSdatasharingacrossmultipleDBCTLsinasingle-ormulti-MVS environment.

v IfyourcurrentCICSissharingdatabaseswithIMS/VSDB/DCor IMS/ESA DM/TMusingIMSdatasharing, itmaybeappropriatetomigratetousingthe IMS/VSDB/DCorIMS/ESADM/TMregionastheDBCTLregion.

Setting up test and production systems for CICS DBCTL

Notethefollowingpointswhensettingupyourtest and/orproductionsystems.

Number of DBCTL subsystems to use

You willneed todeterminethenumberof DBCTLsyourequireina single-MVS environment;forexample,oneDBCTLsubsystemforthewholeMVS image,orone DBCTLsubsystemfor eachCICSsysteminsingle-MVSenvironment.Balance^®the

MVS A MVS B

AORs DOR DBCTL

Figure5.FunctionshippingtoaDORinadifferentMVSimagewithDBCTL

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numberof DBCTLswithina singleMVSimageagainsttheamountofCSAneeded.

Also, beawareof theneed todifferentiateDBCTLsystemsonthesameMVS imageto avoidcausinganyconfusionbetweensubsystems.

You arerecommendedtohave onlyoneproductionDBCTLinasingle-MVS environment.Normally,thisshouldbelargeenoughto serveallCICSTransaction Server forz/OS,Version2 Release3 systemswithinoneMVSimage.For multiple CICSsystemswithlocalandremoteDL/I,runninginseveralMVS imagesusing IMSdatasharing,countthenumberof DL/Ithreadsneeded.If thesum ofthese threads, plusthenumberof expectedactiveBMPsislessthan255,youshould need onlyoneDBCTLwithoutdatasharing.

You needonelogforeach DBCTL,sobearinmind thatloggingcanbecomemore complexthemoreDBCTLsyouhave.Balancetheneedfor multipleDBCTLs against thelogging proceduresyouwillneed. However,logthroughputtimeshould beimprovedcomparedwithlocalDL/I,becauseDBCTLusesthewriteaheaddata set(WADS), whichcanreducetheelapsedtimeneededfor alogwrite.

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Chapter 4. Installing DBCTL, and defining CICS and IMS system resources

This chapterdescribeshowtoinstall DBCTLanddefineCICSandIMSsystem resourcesunderthefollowingsections:

v “ChecklistforinstallingandgeneratingDBCTL”

v “DefiningCICSsystem resourcesforDBCTL”onpage22foraDBCTL

environment,anddescribingtheeffectsonsystemdefinitionsinanexistingDL/I environment

v “GeneratingDBCTL”onpage28,includingsomeexamplesof JCLyoucancopy toprovidea basicDBCTLsubsystem

v “StartingDBCTL, DLISAS,andDBRC”onpage37

v “DefiningtheIMSDRAstartupparametertable”onpage38,includingsome exampleJCL

v “CustomizingDBCTL”onpage42,bymeansofauser-replaceable programand twoglobaluserexits.

Checklist for installing and generating DBCTL

In thischecklist,itisassumedthatyouhavealreadyinstalledCICSTransaction Serverfor z/OS,Version2 Release3 andIMS/ESA6.1or higher,andhavereadthe programdirectoryfor eachproductto checkforanyPTFsorAPARsthatyoumay need, asadvisedintheCICSTransactionServerfor z/OSInstallationGuide.This checklist isanexampletohelpyou developyourown proceduresfor installing DBCTL, dependingontheDBCTLfacilities youwantto use.Whendevelopingyour own checklist,referto theIMSInstallationGuideandtheIMSSystemDefinition Referencemanual manualorIMS/ESAInstallationVolume2:SystemDefinitionand Tailoringfor furtherguidanceonIMSinstallationandsystemdefinition.

CICSsuppliesaDBCTLinstallationverificationprocedure,DFHIVPDB.For more informationabout thisIVP,see theCICSTransactionServerfor z/OSInstallation Guide.

Using DBCTLinsteadof localDL/Isimplifiesinstallation,becauseyoudonothave to performa partialsystem generationofCICStouseDL/I resources.Also,youdo nothave todoapartialsystemgenerationifyouuse remoteDL/I support.

1. PrepareaPDIRthatdoesnot specifyPSBs foranapplicationthatistobe migratedtoDBCTLfortesting. (See“PSBdirectories(PDIRs)”onpage25.) 2. PerformDBCTLstartup.(See“StartingDBCTL, DLISAS,andDBRC”onpage

37.)

3. Updatesystemprocedure libraries;for example,SYS1.PROCLIB, withthe startupproceduresfor DBCTL,DLISAS,DBRC,andtheIRLM(if youareusing it).(ThesestartupproceduresareintheIMS.PROCLIB library.)

4. CheckthatDBCTLhasbeenfullyinstalled,integratedwithMVS,andthatall requiredonlinedata setshavebeen allocatedandinitialized,whereapplicable.

(Forfurtherguidanceondoingthis, seetheIMSInstallationGuide.)

5. PerformanACBgenerationto createmembers oftheIMS.ACBLIB,ifyou have notdone thisalready.

AnACBgenerationshouldhavebeenperformed whenCICSwithlocalDL/I wasmigratedto IMS/ESA3.1orlater.DBCTLcanuseACBsgenerated fora localDL/I (IMS/ESA3.1)environment,butyoushouldnotsimplyinclude

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existingACBLIBsintheDBCTLandDLISASJCL.Useapairofnew,separate, ACBLIBs,whichwillenableyou tousetheIMSonlinechange facility.Youcan copythem from,say,CICS.LOCAL.ACBLIBintoa DBCTL.ONLINE.ACBLIBA andDBCTL.ONLINE.ACBLIBBbut,ifyoudothis, beawarethatyoumight copysomeinvalid(thatis,pre-IMS/ESA3.1)ACBs.Toavoidthis, startwith emptyACBLIBAandACBLIBBlibraries,andregenerateACBs asrequired.

6. Ifyouintendtousedynamicallocation, createDFSMDAmembers.(See“IMS dynamicallocation macro(DFSMDA)”onpage36.)

7. StartDBCTL. DBCTLwillissueastartcommandforDLISASandDBRC.This requirestheDLISASandDBRCJCLprocedurestobeinSYS1.PROCLIB.

(See“StartingDBCTL,DLISAS,andDBRC” onpage 37.)

8. TestDBCTL,for examplebyusingtheDBCTLoperatorcommand/DISPLAYto verifythatDBCTLrecognizesthePSBsandDBDsyou definedintheDBCTL generation.(See“Findingoutcurrentstatusof DBCTLactivities” onpage 63.) 9. Checkyourlogarchivingsetupworksbeforedoinganymoretesting.(See

“LogcontrolwithDBRC” onpage34.)Ifit doesnot,theIMSlogsmay eventuallyfillandstallthesystem.

10. Assemblea DRAthatwillenableCICStoconnect toDBCTL.(See“Defining theIMSDRAstartupparametertable”onpage38.)

11. StartCICSandtesttheconnectionto DBCTL,usingtheCDBC transaction.

(See“CDBC transactionforconnect anddisconnect”onpage48.) 12. GenerateaninitializationPLT,sothatCICScanconnect toDBCTL

automaticallyat startuptime. (See“ConnectingDBCTLto CICSautomatically”

onpage 46.)

13. Testtheapplication(s)youdefinedto DBCTL.

14. Setupandtestrecoveryandrestart ofCICSandDBCTL,anddatabase recovery.(SeeChapter6, “RecoveryandrestartoperationsforDBCTL,” on page73.)

Defining CICS system resources for DBCTL

This sectiontellsyouhowto definesystem resourcesforDBCTL.

v “Systeminitializationparameters”

v “PSBdirectories(PDIRs)”onpage25 v “DDstatements” onpage 25

v “CICS-suppliedgroupswithinCICSsystemdefinition”onpage27 v “Logmanagement”onpage27

v “Monitoringcontroltable(MCT)”onpage27 v “Programlist table(PLT)”onpage27 v “Transientdataqueues”onpage 28

System initialization parameters

TheCICSsysteminitialization parameterscontain informationneededto initialize andcontrolsystem functionsandtheinitialization process.Italso containsmodule suffixes toenableyouto choosebetweendifferentversionsof CICSmodulesand tables.You cangenerateseveralSITsandselecttheonethatbestmeetsyour currentrequirementsat initializationtime. Ifyouhavemorethan oneCICSsystem, each canuseadifferentSIT.

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Specifying DL/I support in system initialization parameters

In CICSTransactionServerforz/OS, Version2Release3,there isnoDLIsystem initialization parameter.Support forDBCTLisalwayspresent.Support forremote DL/I isincludedif thePDIR=YES|xxkeywordisspecified.

Note: ThedefaultisPDIR=NO, meaningthatbydefaultsupportfor remoteDL/I is notincluded.

SeeCICSSystemDefinitionGuideformoredetails abouttheseparameters.

Reviewing CICS system initialization parameters

WithDBCTL, manyCICSsysteminitialization parametersarereplacedbyDBCTL generationparameters,andyouwillneedtochangewhatyouspecifyforothers becauseDL/Icode hasbeenremovedfromtheCICSaddressspace.

Table2 onpage 24liststheCICSsystem initializationparametersrelevantto DL/I.

It stateswhethereachparameterapplies toDBCTLorremoteDL/I(intheDandR columns,respectively).Whereapplicable,itliststhecorrespondingIMSstartup parameter thatappliestoDBCTL. Finally,itmentionsspecialconsiderationsfor DBCTL.

SeetheCICSSystemDefinition Guideforthesyntaxof CICSsystem initialization parameters.See“GeneratingDBCTL”onpage28for moreinformationaboutthe IMSandDBCTLparametersmentionedinthistable.See“DefiningtheIMSDRA startupparametertable” onpage 38for informationaboutDRAstartuptable parameters.

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Table2.CICSsysteminitializationparametersandDBCTL Systeminitialization

parameter

D R IMS/DBCTLstartup parameter

Comments

APPLID Y Y N/A ThegenericVTAM^®applicationidentifierforthis CICSsystem.

DBCTLCON Y N N/A YESspecifiesthatyouwantCICStoconnecttoa DBCTLsubsystemautomaticallyduringCICS initialization.ThiscausesCICStoinvokethe DBCTLattachprogram,DFHDBCON.Theother informationCICSneedsforstartingthe

attachment,suchastheDRAstartuptablesuffixor theDBCTLsubsystemname,istakenfroman INITPARMsysteminitializationparameter.

SpecifyingDBCTLCON=YESmeansyoudonot havetodefinetheDBCTLattachprograminthe CICSpost-initializationprogramlisttable(PLT),as describedin“Programlisttable(PLT)”onpage27.

DSALIM Y Y N/A Upperlimitofthetotalamountofstoragewithin whichCICScanallocatetheindividualdynamic storageareas(DSAs)belowthe16Mbyteline.

SeetheCICSSystemDefinitionGuideandthe CICSPerformanceGuideforinformationabout specifyingDSALIM.SeetheIMSSystem AdministrationGuideforguidanceonDBCTL storageestimates.

EDSALIM Y Y N/A Upperlimitofthetotalamountofstoragewithin whichCICScanallocatetheindividualdynamic storageareas(EDSAs)abovethe16Mbyteline.

Formoreinformation,seetheCICSSystem DefinitionGuideandtheCICSPerformanceGuide forinformationonspecifyingEDSALIM.Seethe IMSSystemAdministrationGuideforguidanceon DBCTLstorageestimates.

INITPARM Y N N/A Usedtopassparameterstoprograms(for

example,PLTprograms)duringCICSstartup.With DBCTL,youcanuseittospecifyDRAstartup parametertablesuffixandDBCTLidentifierto automateconnectiontoaparticularDBCTL.

INITPARMappliestoCOLD,INITIAL,WARM,or EMERGENCYstartsofCICS.WithXRF,

INITPARMappliesonlyiftheactiveCICSwasnot connectedtoDBCTL.Otherwise,thealternate CICSisautomaticallyconnectedtothesame DBCTLastheactive.

PDIR N Y N/A—useAPPLCTN SuffixofthePDIR.WithDBCTL,thePDIRis generatedduringDBCTLgenerationusingthe APPLCTNmacro.

PSBCHK Y Y N/A RequestsPSBauthorizationcheckingofaremote

terminalinitiatingatransactionusingtransaction routing.Toobtainthecheck,youmustalsospecify YESornameontheXPSBsysteminitialization parameter.

CICS IMS Database Control Guide

CICS Transaction Server for z/OS

CICS IMS Database Control Guide

Version 2 Release 3

CICS Transaction Server for z/OS

CICS IMS Database Control Guide

Version 2 Release 3

Contents

Preface

Who this book is for

What this book is about

What you need to know before reading this book

How to use this book

Terms used

Summary of changes

Chapter 1. Overview of Database Control (DBCTL)

Summary of the benefits of DBCTL

Overview of DL/I request handling in CICS

Connecting to DBCTL

CICS-IMS DBCTL environment

CICS-IMS DBCTL environment—description of components

CICS-DBCTL interface control components in CICS address space

CICS-DL/I router (DFHDLI)

CICS database adapter transformer (DFHDBAT)

Database resource adapter (DRA)

Components of DBCTL in IMS address spaces

DBCTL

DL/I separate address space (DLISAS)

Database Recovery Control (DBRC)

Internal resource lock manager (IRLM)

Summary of DBCTL components in CICS and IMS

Coordinator control subsystem (CCTL)

Resources you can access from a CICS environment that includes DBCTL

Chapter 2. Benefits of using DBCTL

Functional benefits of DBCTL

Data availability

Batch message processing programs (BMPs)

System service requests

Access to data entry databases (DEDBs)

System availability benefits of DBCTL

Release independent interface

Improved sharing of databases between multiple CICS systems

Failure isolation

Operational flexibility

Online image copy utility

Online change utility

Online reorganization for DEDBs

Ability to use XRF

Performance benefits of DBCTL

Virtual storage constraint relief

Improved throughput on multiprocessors

Chapter 3. Migration considerations for DBCTL

Other methods for accessing DL/I

Withdrawn support of local DL/I and shared database

CICS-IMS release compatibility

Possible migration paths to CICS Transaction Server for z/OS, Version 2 Release 3 with DBCTL

CICS with local DL/I

CICS with local DL/I and data sharing

CICS with shared database

CICS with IMS data sharing and batch

CICS with function shipping

CICS with IMS/ESA DM/TM

Scenario 1

Scenario 2

Suggested migration procedure to DBCTL

Planning your new DBCTL setup

Setting up test and production systems for CICS DBCTL

Number of DBCTL subsystems to use

Chapter 4. Installing DBCTL, and defining CICS and IMS system resources

Checklist for installing and generating DBCTL

Defining CICS system resources for DBCTL

System initialization parameters

Specifying DL/I support in system initialization parameters

Reviewing CICS system initialization parameters